The relation of body mass index and abdominal adiposity with dyslipidemia in 27 general populations of the WHO MONICA Project.

The association between adiposity measures and dyslipidemia has seldom been assessed in a multipopulational setting. 27 populations from Europe, Australia, New Zealand and Canada (WHO MONICA project) using health surveys conducted between 1990 and 1997 in adults aged 35-64 years (n = 40,480). Dyslipidemia was defined as the total/HDL cholesterol ratio >6 (men) and >5 (women). Overall prevalence of dyslipidemia was 25% in men and 23% in women. Logistic regression showed that dyslipidemia was strongly associated with body mass index (BMI) in men and with waist circumference (WC) in women, after adjusting for region, age and smoking. Among normal-weight men and women (BMI<25 kg/m(2)), an increase in the odds for being dyslipidemic was observed between lowest and highest WC quartiles (OR = 3.6, p < 0.001). Among obese men (BMI ≥ 30), the corresponding increase was smaller (OR = 1.2, p = 0.036). A similar weakening was observed among women. Classification tree analysis was performed to assign subjects into classes of risk for dyslipidemia. BMI thresholds (25.4 and 29.2 kg/m(2)) in men and WC thresholds (81.7 and 92.6 cm) in women came out at first stages. High WC (>84.8 cm) in normal-weight men, menopause in women and regular smoking further defined subgroups at increased risk. standard categories of BMI and WC, or their combinations, do not lead to optimal risk stratification for dyslipidemia in middle-age adults. Sex-specific adaptations are necessary, in particular by taking into account abdominal obesity in normal-weight men, post-menopausal age in women and regular smoking in both sexes.

Intercellular calcium waves in primary cultured rat mesenteric smooth muscle cells are mediated by connexin43.

Intercellular Ca(2+) wave propagation between vascular smooth muscle cells (SMCs) is associated with the propagation of contraction along the vessel. Here, we characterize the involvement of gap junctions (GJs) in Ca(2+) wave propagation between SMCs at the cellular level. Gap junctional communication was assessed by the propagation of intercellular Ca(2+) waves and the transfer of Lucifer Yellow in A7r5 cells, primary rat mesenteric SMCs (pSMCs), and 6B5N cells, a clone of A7r5 cells expressing higher connexin43 (Cx43) to Cx40 ratio. Mechanical stimulation induced an intracellular Ca(2+) wave in pSMC and 6B5N cells that propagated to neighboring cells, whereas Ca(2+) waves in A7r5 cells failed to progress to neighboring cells. We demonstrate that Cx43 forms the functional GJs that are involved in mediating intercellular Ca(2+) waves and that co-expression of Cx40 with Cx43, depending on their expression ratio, may interfere with Cx43 GJ formation, thus altering junctional communication.

Artificial muscle: the human chimera is the future.

Severe heart failure and cerebral stroke are broadly associated with the impairment of muscular function that conventional treatments struggle to restore. New technologies enable the construction of "smart" materials that could be of great help in treating diseases where the main problem is muscle weakness. These materials "behave" similarly to biological systems, because the material directly converts energy, for example electrical energy into movement. The extension and contraction occur silently like in natural muscles. The real challenge is to transfer this amazing technology into devices that restore or replace the mechanical function of failing muscle. Cardiac assist devices based on artificial muscle technology could envelope a weak heart and temporarily improve its systolic function, or, if placed on top of the atrium, restore the atrial kick in chronic atrial fibrillation. Artificial sphincters could be used to treat urinary incontinence after prostatectomy or faecal incontinence associated with stomas. Artificial muscles can restore the ability of patients with facial paralysis due to stroke or nerve injury to blink. Smart materials could be used to construct an artificial oesophagus including peristaltic movement and lower oesophageal sphincter function to replace the diseased oesophagus thereby avoiding the need for laparotomy to mobilise stomach or intestine. In conclusion, in the near future, smart devices will integrate with the human body to fill functional gaps due to organ failure, and so create a human chimera.

Endogenous cannabinoid receptor CB1 activation promotes vascular smooth-muscle cell proliferation and neointima formation.

Percutaneous transluminal angioplasty is frequently used in patients with severe arterial narrowing due to atherosclerosis. However, it induces severe arterial injury and an inflammatory response leading to restenosis. Here, we studied a potential activation of the endocannabinoid system and the effect of FA amide hydrolase (FAAH) deficiency, the major enzyme responsible for endocannabinoid anandamide degradation, in arterial injury. We performed carotid balloon injury in atherosclerosis-prone apoE knockout (apoE(-/-)) and apoE(-/-)FAAH(-/-) mice. Anandamide levels were systemically elevated in apoE(-/-) mice after balloon injury. ApoE(-/-)FAAH(-/-) mice had significantly higher baseline anandamide levels and enhanced neointima formation compared with apoE(-/-) controls. The latter effect was inhibited by treatment with CB1 antagonist AM281. Similarly, apoE(-/-) mice treated with AM281 had reduced neointimal areas, reduced lesional vascular smooth-muscle cell (SMC) content, and proliferating cell counts. The lesional macrophage content was unchanged. In vitro proliferation rates were significantly reduced in CB1(-/-) SMCs or when treating apoE(-/-) or apoE(-/-)FAAH(-/-) SMCs with AM281. Macrophage in vitro adhesion and migration were marginally affected by CB1 deficiency. Reendothelialization was not inhibited by treatment with AM281. In conclusion, endogenous CB1 activation contributes to vascular SMC proliferation and neointima formation in response to arterial injury.

Mini invasive skeletal muscle biopsy technique with a tri-axial end cut needle.

OBJECTIVE: Skeletal Muscle Biopsy is a minor surgical procedure for the diagnosis of different neuromuscular pathological conditions and has recently gained popularity also in the research field of age-related muscular modifications and sarcopenia. Few studies focused on the application of mini-invasive muscular biopsy in both normal and pathological conditions. The aim of our study was to describe a mini invasive ultrasound-guided skeletal muscular biopsy technique in complete spinal cord injured (SCI) patients and healthy controls with a tri-axial end-cut needle. PATIENTS AND METHODS: Skeletal muscle biopsies were collected from 6 chronic SCI patients and 3 healthy controls vastus lateralis muscle with a tri-axial end cut needle (Biopince© - Angiotech). Muscle samples were stained for ATPase to determine fibers composition, moreover, gene expression of cyclooxygenase-1 (COX-1) and prostaglandin E2 receptor has been analyzed by Real Time RT-PCR. RESULTS: All the procedures were perfomed easily without failures and complications. Control tissue was macroscopically thicker than SCI one. Control specimen displayed an equal distribution of type I and type II fibers, while SCI sample displayed a prevalence of type II fibers SCI specimen displayed a significant reduction in COX-1 gene expression. This mini-invasive approach was easy, accurate and with low complication rate in performing skeletal muscle biopsy in both SCI patients and controls. CONCLUSIONS: This technique could be useful in conditions in which the overall quantity of specimen required is small like for molecular biology analysis. For histological diagnostic purposes and/or conditions in which the original tissue is already pathologically modified, this technique should be integrated with more invasive techniques.

The role of cyclic nucleotides in modulation of crayfish neuromuscular junctions by a neuropeptide /

DF2, a heptapeptide, is a member of the family of FMRFamide-like peptides and has been shown to increase the amount of transmitter released at neuromuscular junctions of the crayfish, Procambarus clarkit Recent evidence has shown that protein kinase C (PKC), calcium/calmodulin-dependent protein kinase II (CaMKII) and the cAMPdependent protein kinase (PKA) play a role in the neuromodulatory pathway of DF2. The involvement of these kinases led to the prediction that a G-protein-coupled receptor (GPCR) is activated by DF2 due to the role that each kinase plays in traditional GPCR pathways seen in other organisms and in other cells. G-proteins can also act on an enzyme that generates cyclic guanosine monophosphate (cGMP) which mediates its effects through a cGMP-dependent protein kinase (PKG). This thesis addresses the question of whether or not DF2's effects on synaptic transmission in crayfish are mediated by the cyclic nucleotides cAMP and cGMP. The effects of DF2 on synaptic transmission were examined using deep abdominal extensor muscles of the crayfish Procambarus clarkii. An identified motor neuron was stimulated, and excitatory post-synaptic potentials (EPSPs) were recorded in abdominal extensor muscle LI . A number of activators and inhibitors were used to determine whether or not cAMP, PKA, cGMP and PKG mediate the effect of this peptide. Chemicals that are known to activate PKA (Sp-cAMPS) and/or PKG (8-pCPTcGMP) mimic and potentiate DF2's effect by increasing EPSP amplitude. Inhibitors of either PKA (Rp-cAMPS) or PKG (Rp-8-pCPT-cGMPS) block a portion of the increase in EPSP amplitude induced by the peptide. When both kinase inhibitors are applied simultaneously, the entire effect of DF2 on EPSPs is blocked. The PKG inhibitor blocks the effects of a PKG activator but does not alter the effect of a PKA activator on EPSP amplitude. Thus, the PKG inhibitor appears to be relatively specific for PKG. A trend in the data suggests that the PKA inhibitor blocks a portion of the response elicited by the PKG activator. Thus, the PKA inhibitor may be less specific for PKA. Phosphodiesterase inhibitors, which are known to inhibit the breakdown of cAMP (IBMX) and/or cGMP (mdBAMQ), potentiate the effect of the peptide. These results support the hypothesis that cAMP and cGMP, acting through their respective protein kinase enzymes, mediate the ability of DFi to increase transmitter output.

The influence of skeletal muscle cell volume on the regulation of carbohydrate uptake and muscle metabolism

This study investigated the regulation of carbohydrate metabolism and glucose uptake through changes in skeletal muscle cell volume. Using an established invitro isolated whole muscle model, soleus (SOL) and extensor digitorum longus (EDL) muscles were dissected from male rats and incubated in an organ bath containing Sigma medium-199 with 8 mM D-glucose altered to target osmolality (hypo-osmotic: HYPO, iso-osmotic: ISO, hyper-osmotic: HYPER; 190, 290, 400 mmol/kg). Muscles were divided into two groups; metabolite (MM) and uptake (MU). MM (N=48) were incubated for 60 minutes and were then immediately flash frozen. MU (N=24) were incubated for 30 minutes and then the extracellular fluid was exchanged for media containing ^H-glucose and ^'*C-mannitol and incubated for another 30 minutes. After the incubation, the muscles were freeze clamped. Results demonstrated a relative water decrease and increase in HYPER and HYPO, respectively. EDL and SOL glucose uptakes were found to be significantly greater in HYPER conditions. The HYPER condition resulted in significant alterations in muscle metabolite concentrations (lower glycogen, elevated lactate, and G-6-P) suggesting a catabolic cell state, and an increase in glycogen synthase transformation when compared to the HYPO group. In conclusion, skeletal muscle cell volume alters rates of glucose uptake with further alterations in muscle metabolites and glycogen synthase transformation.

The effects of R(+)-lipoic acid supplementation on regulation of human skeletal muscle pyruvate dehydrogenase

This thesis investigated whole body glucose disposal and the adaptive changes in skeletal muscle carbohydrate metabolism following 28 d of supplementation with 1000 mg R(+)-lipoic acid in young sedentary males (age, 22.1 ± 0.67 yr, body mass, 78.7 ± 10.3 kg, n=9). In certain individuals, lipoic acid decreased the 180-min area under the glucose concentration and insulin concentration curve during an oral glucose tolerance test (OGTT) (n=4). In the same individuals, lipoic acid supplementation decreased pyruvate dehydrogenase kinase activity (PDK) (0.09 ± 0.024 min"^ vs. 0.137 ± 0.023 min'\ n=4). The fasting levels of the activated form of pyruvate dehydrogenase (PDHa) were decreased following lipoic acid (0.42 ± 0.13 mmol-min'kg'^ vs. 0.82 ± 0.32 mmolrnin'^kg"\ n=4), yet increased to a greater extent during the OGTT (1.21 ± 0.34 mmol-min'kg"' vs. 0.81 ±0.13 mmolmin"'kg'\ n=4) following hpoic acid supplementation. No changes were demonstrated in the remaining subjects (n=5). It was concluded that improved glucose clearance during an OGTT following lipoic acid supplementation is assisted by increased muscle glucose oxidation through increased PDHa activation and decreased PDK activity in certain individuals.

The capillary supply of human skeletal muscle in health and disease

BACKGROUND: Capillaries function to provide a surface area for nutrient and waste exchange with cells. The capillary supply of skeletal muscle is highly organized, and therefore, represents an excellent choice to study factors regulating diffusion. Muscle is comprised of three specific fibre types, each with specific contractile and metabolic characteristics, which influence the capillary supply of a given muscle; in addition, both environmental and genetic factors influence the capillary supply, including aging, physical training, and various disease processes. OBJECTIVE: The present study was undertaken to develop and assess the functionality of a data base, from which virtual experiments can be conducted on the capillary supply of human muscle, and the adaptations of the capillary bed in muscle to various perturbations. METHODS: To create the database, an extensive search of the literature was conducted using various search engines, and the three key words - "capillary, muscle, and human". This search yielded 169 papers from which the data for the 46 variables on the capillary supply and fibre characteristics of muscle were extracted for inclusion in the database. A series of statistical analyses (ANOVA) were done on the capillary database to examine differences in skeletal muscle capillarization and fibre characteristics between young and old individuals, between healthy and diseased individuals, and between untrained, endurance trained, endurance welltrained, and resistance trained individuals, using SAS. RESULTS: There was a significantly higher capillarization in the young compared to the old individuals, in the healthy compared to the diseased individuals, and in the endurance-trained and endurance well-trained compared to the untrained individuals. CONCLUSIONS: The results of this study support the conclusion that the capillary supply of skeletal muscle is closely regulated by factors aimed at optimizing oxygen and nutrient supply and/or waste removal in response to changes in muscle mass and/or metabolic activity.

Adaptations of skeletal muscle pyruvate dehydrogenase kinase in response to food-restriction in mitochondrial subpopulations

University, 2006 Dr. Sandra J. Peters Pyruvate dehydrogenase (PDH) catalyses the decarboxylation of pyruvate, to form acetyl-CoA. PDH activity is down-regulated by intrinsic PDH kinases (predominantly PDK2 and PDK4 isoforms), but the understanding of the PDK isoform distribution and adaptation to nutritional stresses has been restricted to mixed mitochondrial populations, and not delineated between subsarcolemmal (SS) and intermyofibrillar (IMF) subpopulations. SS and IMF mitochondria exhibit distinct morphological and biochemical properties; however the functional differences are not well understood. This study investigated the effect of fed (FED) versus 48 h total foodrestriction (FR) on rat red gastrocnemius muscle PDK2 and 4 isoform content in SS and IMF mitochondria. PDK4 content was ~3-5 fold higher in SS mitochondria compared to IMF (p=0.001), and increased with FR -3-4- fold in both subpopulations (p<0.001). PDK2 was -2.5-4 fold higher in SS mitochondria compared to IMF (p=0.001), but PDK2 was unaltered with FR. Citrate synthase activity (|imol/min/mg mitochondrial protein) was not different between either subpopulation. As well there were no significant differences between mitochondrial subpopulations in PDH complex components in both fed and FR states. These results demonstrate that there is a markedly higher content of both PDK isofonns in SS compared to IMF mitochondria. Although PDK2 does not increase in either subpopulation in response to FR, PDK4 increases to a similar extent in both SS and IMF after 48 h food-restriction.

Skeletal muscle fibre-type comparison of whole tissue and subcellular membrane phospholipids and fatty acids

Membranes are dynamic structures that affect cell structure and function. Compositional changes ofmembranes have been shown with the application of a perturbation; however these are limited to whole tissue analysis. The purpose of this thesis was to compare the phospholipid (PL) fatty acid (FA) composition of rat whole muscle (Wm) to 1) purified and non-purified subsarcolemmal (SS) mitochondria in soleus, plantaris, and red gastrocnemius, and 2) sarcolemma, transverse-tubules, SS and intermyofibrillar (IMF) mitochondria fix)m whole hindlimb. The major findings were that 1) contamination significantly altered the PL FA composition of the SS mitochondrial membrane fraction, 2) Wm and SS mitochondria compositions differed between muscle types, and 3) Wm did not accurately reflect the PL FA composition of any isolated subcellular membranes, with each being unique from each other. As such, the relevancy of the trends reported in the literature of the effects of perturbations on Wm may be limited.